The Fernandes e Abreu law firm say their client initially told them she had had consensual sex with Neymar, the world's most expensive footballer, in a Paris hotel in May and that he then became violent and assaulted her.
But the lawyers said that in the official complaint the women gave to the Brazilian police, the woman "described what had happened as 'rape', which is a completely different allegation".
Neymar posted a seven-minute video on Instagram on Saturday vehemently denying he had raped the woman.
In the video, he showed a string of WhatsApp messages he said he had received from the Brazilian woman. He also named her and showed what he said were photographs of her topless and apparently in his hotel bed.
Police in Rio said Sunday they had launched an investigation into the publication of intimate information on social media concerning the women.
The player's father has claimed he is the victim of blackmail.
Neymar, who was transferred to PSG from Barcelona for a world-record 222 million euros ($248.5 million) in 2017, is currently in Brazil preparing for the Copa America, which takes place in the country from June 14 to July 7.
His 2018-2019 season with PSG was blighted by injury and he courted controversy by lashing out at a supporter after the club suffered a shock defeat in the French Cup final.